For this project, we are building a "ticking bomb", with just a few components and reusing the box we received the build night tools.
Step 1: Electronic circuit
Bill of materials:
* 555 timer
* 47kOhm resistor
* 2x10uF capacitor
* 8Ohm speaker
* 9V battery
Can use higher capacitor value for C1 to slow the ticking down (or smaller to speed it up).
We assembled it on a breadboard, but could solder it as well.
Step 2: Package and give it to someone
In my experience, the ticking sounds better inside the box, than the outside of it, maybe the muffling effect of it makes it cooler.
Enjoy the "bomb", and don't ship it!